Plastic spring

ABSTRACT

A plastic spring consists essentially of a spring support, a web rigidly supported on the spring support, a first spring tongue attached to the web, and at least one auxiliary spring tongue extending from the web between the first spring tongue and the spring support, the spring tongues being parallel to each other. The spring characteristic of such a plastic spring may be adapted to different conditions independently of the material.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a plastic spring, consisting of a springtongue attached to a spring support by means of a web.

2. Description of the Prior Art

Plastic springs can be used for many purposes, and they are employed forinstance in tablet dispensers as a return spring for the tablet ejector.These plastic springs are mostly injection-molded in one singleoperation together with the spring support, and up to now have consistedof a bow-shaped web ending as a spring tongue at its free end. Forsafety reasons a material must be chosen for the production of theplastic spring and the spring support, which in case of rupture does notinvolve a risk of injury by sharp edges, pointed parts or the like, sothat the material properties of the used plastic material cannot beadjusted to the required spring properties. Therefore, the known plasticsprings are often too weak and cannot satisfy the requirements asregards the spring deflection and the spring force.

SUMMARY OF THE INVENTION

It is thus the object underlying the invention to eliminate thesedeficiencies and create a plastic spring as described above, which caneasily be injection-molded from the same material as the associatedspring support, and whose spring properties can nevertheless easily beadapted to different conditions.

This object is solved by the invention in that the web is rigidlysupported with respect to the spring support, and at least one auxiliaryspring tongue parallel to the spring tongue extends from the web belowthe spring tongue. The spring tongue and auxiliary spring tonguesconstitute a cooperating spring assembly, whose spring force increasesthe more spring is deflected, since the deflecting spring tongue issupported by the underlying auxiliary spring tongue under a load then toand then to the spring force of the auxiliary spring tongue is added tothe spring force of the spring tongue. This increase in spring force canbe adjusted to the desired conditions by the number of auxiliary springtongues, and the extent of the deflection may be influenced by means ofthe distance between the spring tongue and auxiliary spring tongue. Theplastic spring can therefore be injection-molded from a suitablematerial which is break-proof even under higher loads, the dangerouspoint of attachment of the web is secured by rigidly supporting the webon the spring support.

When the spring tongue and the auxiliary spring tongues have a lengthwhich decreases towards the spring support, the stiffness increasingwith decreasing length results in a progressive increase in spring forcewith increasing defection of the spring, and there is in additionachieved a space-saving arrangement of the auxiliary spring tonguesbelow the spring tongue.

For properly utilizing the material properties, the spring tongue andthe auxiliary spring tongues have a width tapering towards the free endof the tongue, so that the material stresses can be uniformlydistributed over the length of the tongue when a load is acting on thespring.

It is also advantageous to provide lateral supporting cheeks between weband spring support, as these supporting cheeks do not only providestability of the web support, but a protective housing is formed betweenthe supporting cheeks and the web for the spring tongue and theauxiliary spring tongues.

BRIEF DESCRIPTION OF THE DRAWING

In the drawing, the subject-matter of the invention is represented byway of example, wherein:

FIGS. 1 and 2 illustrate an inventive plastic spring in a schematic sideview and top view, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A plastic spring 1, which is injection-molded together with the springsupport 2, for instance a tablet dispenser magazine, consists of a web 3attached to the spring support 2, which web verges into a transverselyextending spring tongue 4, and from which below the spring tongue 4 forinstance two auxiliary spring tongues 5, 6 protrude in the samedirection. The auxiliary spring tongues 5, 6 are shorter than the springtongue 4, and the length of these auxiliary spring tongues graduallydecreases with increasing distance from the spring tongue 4. Inaddition, the widths of the spring tongue 4 and the auxiliary springtongues 5, 6 can taper towards the free end of the tongue, as isindicated in FIG. 2 in dash-dotted lines. To provide a rigid support,the web 3 is connected with the spring support 2 by means of lateralsupporting cheeks 7, so that a kind of spring housing is formed by thesupporting cheeks 7 and the web 3.

The spring tongue 4 and the auxiliary spring tongues 5, 6 constitute aspring assembly, whose individual spring tongues progressively cooperatestep by step under a load K, so that in dependence on the springdeflection an increasing spring force is achieved (dash-dottedrepresentation in FIG. 1). It is thus possible to produce a plasticspring injection-molded from the same material as the spring support,whose spring characteristic can easily be adapted to the respectiverequirements as regards spring deflection and spring force.

We claim:
 1. An integral plastic spring consisting essentially of(a) aspring support, (b) a web rigidly supported on the spring support, (c) afirst spring tongue attached to the web, and (d) at least one auxiliaryspring tongue attached to, and extending from, the web between the firstspring tongue and the spring support,(1) the spring tongues beingparallel to each other, spaced from each other for free movement inrelation to each other, and extending transversely to the web.
 2. Theplastic spring of claim 1, wherein the spring tongues have a lengthdecreasing towards the spring support.
 3. The plastic spring of claim 1,wherein the spring tongues have a width tapering towards the free endsthereof.
 4. A plastic spring consisting essentially of(a) a springsupport, (b) a web rigidly supported on the spring support, (c) a firstspring tongue attached to the web, (d) at least one auxiliary springtongue extending from the web between the first spring tongue and thespring support,(1) the spring tongues being parallel to each other, and(e) lateral supporting cheeks arranged between the spring support andthe web.